Color photography



Nov. 29,1932. w VAN ELL 1,889,124

COLOR PHOTOGRAPHY Filed April 24, 1929 ALTER AT A D AND RLTERNRTE H'FIRDaruD ALTERNRT'E HARD/7ND 50FT STRIPS op-r 5TRIP5I/(F'RRMES Jar-T IlllFRAMES WW D D D D D 6 D D o D o 1: D D

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TRANS PHREN'T' BFI'SE PROTECT g0 kflYE? PPINCHROMHT'Q EMUL. 5 N

, Inventor; A Wb'ZZLam Yflnflorezz KZZqy,

Attorney.

Patented Nov. 29, 1932 UNITED sTATEs PATENT OFFICE WILLLAM VAN DORENKELLEY, OF HOLLYWOOD, CALIFORNIA, ASSTGNOR, MESNE ASSIGNMENTS, TO DUCHROME FILM SYSTEM LTIO OF HOLLYWOOD, CALIFORNIA,

A CORPORATION OF CALIFORNIA.

Application filed April 24,

y In this specification, and the accompanying drawing, I shall describeand show a pre- 7 ferred formof my invention, and specifically I mentioncertain of its mo re important objects. I do notlimit myselfto the formsdisclosed, since various changes and adaptations may be made thereinwithout departing from the essenceof my invention as hereinafterclaimed; and objectsand advantages, Q other than those specificallymentioned, are

included within its scope.

This invention relates to color-photography and the allied photographicarts. Its principal -objects include: first, to provide new and improvedmeans for producing photographic representations of objects in theirnatural colors; and, second, to supply a new type of photographic filmor plate, that is particularly adapted'for' use in connection with thisart.

My objects are attained in the manner illustrated in the accompanyingdrawing, in which- Figures 1, 2, and 3 are front elevations 1 ofportions of a motion picture film, illustrative of intermediate step inthe process of modifying it to employ the principles of my invention;and

Figure 4 is an enlarged cross-section of '30 the above film whencompleted.

All of the figures are diagrammatic, and are greatly distorted as toscale for convenience of illustration. Similar reference numerals referto similar parts throughout. the several views.

Proceeding to a detailed description of my invention, we will assumethat it is to be used in connection with a standard positive mo- 40 tionpicture film of commerce. The first step will be to produce in theemulsion of such a film, very closely spaced parallel lines of reducedsilver, throughout its area; the width of the'lines being approximatelyequal to the width of the spaces therebetween. This very narrow parallelstrips of clear glass,

coma i'noroeaermz 1929. Serial No. 357,702

may be accomplished in various well known ways.1For instance, anoriginal line screen a may be made on glass by ruling lines there onwith a diamond point, and then blackening such lines. The number oflines may be anywhere from 400 to 1200 per inch, and their width in anycase is made equal to that of the spaces between them. Thus one half thetotal area of such a screen will comprise and the other half of the areawill comprise narrow black bands of the same width, between the clearstrips.

If a photosensitized emulsion is exposed throughsuch a screen, incontact therewith, and then developedymetallic silver will be formed inthe emulsion in narrow parallel lines, corresponding in width and pitchto the clear strips of the screen. Any suitable developer may be used;but one that gives cgntrast, a fine grain, and that has no hardeningaction on the emulsion, is to be preferred After development, theunexposed silver in the emulsion is removed in a bath of sodiumthiosulfate. I

v The film is then placed in a bath composed of: potassium bichromate 8grammes; cupric chloride 24 grammes; sodium chloride grammes; and Water1 liter. Such a bath acts to bleach the reduced silver lines of thefilm, and to harden the gelatine in the immediate vicinity thereof. Thehardened portions of the gelatine will have had two propertes impartedto them, viz.: the propertyto absorb and fix certain classes of dyes,that do not stain or affect the interposed soft portions of thegelatine; and the prop erty to repel certain other dyes of a diiferentclass, that are capable of being absorbed by, and of coloring, said softportions. The film is then placed in a bath of sodium thiosulfate, forremoving the bleached image, and is dried afterward. At this stage ofthe' process the film is perfectly clear and transparent; but,nevertheless, is in effect a species of diflraction.grating,-by reasonof its alternate strips of hardened and soft gelatine.

The next step in the process is to treat the film in a bath comprising 3grammes of Patstrips of the gelatine; and the red dye will stain thesoft gelatine. There will be a remarkably sharp separation of the colorsin the film, by reason of the treatment to which the gelatine has beensubjected. and the inherent, properties of the dyes. The red dye willhave but very little, if any, tendency to stain the hardened portions ofthe gelatine; and the blue dye will have correspondingly little tendencyto stain the soft portions. After dyeing in this manner, the film isthoroughly washed, dried, and given a thin coat of transparent varnishto protect the. dyed emulsion from alteration during subsequentprocesses.

p The final operation in the preparation of the film to adapt it to thepurposes of my invention, is to apply a photosensitized emulsion to thevarnished surface. Such emulsion should be one that is sensitive to thecolors used for dyeing the strips of the film described above, that is,the emulsion should be panchromatic.

, Films, produced in the mannerdescribed, are illustrateddiagrammatically in the accompanying drawing. The figures are great- 1ydistorted in scale, as stated above, in order to disclose the inventionmore conveniently. Many variations of detail of the process described,may be utilized without affecting the results essentially, or departingfrom the scope of the invention. Thus in Fig. 1, the

hardened strips 5 of the gelatine, after treatment in the bichromate andfixing baths, and the soft interposed gelatine strips 6, are, shown asrunning longitudinally of the film 7 In.Fig. 2, similar hard and softstrips, 5 and 6 respectively, are shown running longitudinally of thefilm 8 on alternate frames;

and corresponding hard and soft strips 9 I and l0 respectively are shownas running transversely of the film on the interposed frames. In Fig. 3the strips 11 and 12 run diagonally of the film 13 in one direction inalternate frames, and corresponding strips 14 and 15 run diagonally inthe other direction on the interposed frames. In such films as thoseillustrated in Figs. 2 and 3, where the strips of alternate frames runin different directions, it is desirable that the angle between therespective directions should be about ninety'degrees. It is to be notedthat a film having diagonal strips, arranged in the manner of Fig. 3, isusually to be preferred to one having transverse or longitudinallyarranged strips.

' It is also to be remarked that, instead of altering thematerial of the,film so. as to be composed of alternate hard and soft straight strips,use may be inade of otherwise shaped areas of regular or irregular form.The important thing is to have about half the gelatine area hardened anddivided into small spaced areas, evenly distributed; and the other halfof the gelatine area soft, and occupying the spaces between the hardenedportions.

Vhen use is made of strips arranged as shown in Figs. 2 or 3, there isan advantage gained by reason of the additive color effect due topersistence of vision. Thus, in addition to the two elementary colors ofthe strips, there will be composite colors due to the apparent crossingof the strips resulting from persistense of vision. "That is to say,where the strips appear to cross, the colors therein will appear to besuperposed, at the intersections, and will produce a composite coloreffect. Further variation of color effects may be obtained by making thedensity of the primary colors of one set of alternate frames, slightlydifferent from the density of the colors in the intermediate frames.

Fig. 4 is a much enlarged and distorted cross-section of such a film ashas been described herein, wherein the transparent base -is shown at 16,hardened blue-dyed portions of the treated gelatine at 17, soft red-dyed"portions of the gelatine at 18, the protecting varnish layer at 19, andthe panchromatic -photosensitized emulsion at 20.

Having prepared a film as above described and illustrated, it may beused in various ways related to the art of color photography. As anexample, two black and white negatives could first be prepared, in everyrespect similar to each other except as to the exposure values in thoseareas where colors were photographed. Thus, if panchromatic negativesare used, one could be exposed through ablue-green screen, and the otherthrough a red-orange screen. One negative will then be minus thered-orange color values, and the other will bepminus the blue-greenvalues. Each negative will have failed to record certain colors but didphotograph everything else. The other negative did the same thing withrespect to the complementary group of colors.

Such negatives are then employed for print-exposing emulsion 20 of myspecially prepared film. Both the red-minus and the blue-minusnegativesare used for this purpose, the exposures being made insuperposed registering positions, and through transparent base 16'. Theexposures may be effected by direct contact printing, white light forthe purpose coming in the direction of arrow 21; Or the exposures may beaccomplished in other well known ways, as by the use of lenses at 22.The red-minus negative is printed with red light, and the blue-minusnegative is printed with blue light; each light being of such characterthat no printing will occur under the film strips of complementarycolor.

After being exposed as above, emulsion 20 is developed and fixed in theusual photographic manner. We will then have a film comprising verynarrow transparent bands, colored alternately with complementary colors;and a black and white image behind the bands, resulting from twocolor-selective exposures through them. Such a film when viewed bytransmitted light which originally comprises the full spectrum, willshow the object; photographed in its natural colors, both elementary andcomposite. It may also be used to project a naturally colored pictureupon aiscreen. Still other uses will suggest themselves to those who areinterested in this art.

In the case of a motion picture film, the successive frames may carrydiflerent combinations of colors that are not necessarily complementalas to each frame; but the additive effect of all the colors of adjacentframes should be such that, upon projection, a substantial whitewillapparently be seen, by reason of persistenceof vision. Thus oneframe mightcarry blue-violet and orange areas, and appear to be ofmagenta color. The succeeding frame might then carry red and-green,resulting in ayellowish green shade. These four colors when effectivelysuperposed upon a screen, by reason of persistence of vision, willappear as white.

It will readily be understood that the generic invention that I havedisclosed is susceptible of many specific variations. Some of these havebeen described herein, and others will occur to those familiar with theart involved. Other dyes may be used in the places of those mentioned;and other chemical treating baths, adapted for producing the desiredeffects, may be employed. The complementary colored portions of the film.may be variously shaped, disposed, andproportfoned; and thecolor-selective exposures of emulsion 20 may be effected in several wellknown ways. Therefore I claim the generic invention broadly, and do notlimit myself to the specific disclosures herein, except as set forth inthe appended claims.

I claim as my invention:

1. The method of treating a photo-sensitized silver-halide emulsionwhich consists in exposing, developing and bleaching it in turn, in amanner to harden the exposed portions; removing all silver and itsproducts in exposing, developingjbleaching, and 'fix-' ing it in turn,in a manner to make the exposed portionsdye-selective; and then dyeingthe emulsion in a bath containing two dyes; one of said dyes beingadapted to color said exposed portions only; and the other dye beingadapted to impart a complemental color to the unexposed portions only.

3. The method of treating a photo-sensi-' tized silver-halide emulsion.which consists in exposing, developing, bleaching, and fixing it inturn, in a manner to harden the exposed portions only and to make themdye selective; and then dyeing the emulsion in a bath containing twodyes, of which one is red-orange and the other blue-green; one of saiddyes being adapted to color said hardened portions only; and the otherdye being adilpted to color the unhardened portions on y.

4. The'method of treating a photo-sensitized silver-halide emulsionwhich consists in exposing and developing it in a manner to produce amultiplicity of small uniformly distributed spaced images; bleaching thereduced silver of said'images in a manner to give the correspondingportions of the emulsion" dye-selective qualities; fixing the emulsion;and then dyeing the emulsion in a bath containing two dyes ofcomplemental colors and different characteristics; one of said dyesb-eingadapted to color said portions only; and the other dye beingadapted to color the remaining portions of the emulsion only.

5. The method of treating a photo-sensitized silver-halide emulsionwhich consists in exposing and developing it in a manner to produce amultiplicity of small developed images that are spaced and uniformlydistributed; bathing the emulsion in a solution adapted to bleach thereduced silver of said images and to impart to corresponding portions ofthe emulsion an ability to absorb dyes of a certain group whilerepelling dyes of another group; fixing the emulsion; dyeing saidportions by means of a suitable dye of the first said group; and dyeingthe remaining portions of the emulsion by means of a dye of complementalcolor of the second said group.

6. The method of treating a photo-sensitized silver-halide emulsionwhich consists in exposing and developing it in a manner to produce amultiplicity of small developed sponding portions of the emulsion anability to" absorb dyes of a certain group while repelling dyes ofanother group; fixing the emulsion; and then bathing the emulsion in asolution containing a dye of each of said groups; the dyes in the lastsaid solution being of complemental colors.

7. The method of treating a photo-sensitized silver-halide emulsionwhich consists in exposing and developing it to produce a multiplicityof small and uniformly dis tributed spaced images; bathing the emulsionin a solution of copper bichromate and sodium chloride to bleach thereduced silver, and

to make the corresponding portions of the emulsion absorbent to an aciddye; fixing the entire emulsion in suchmanner as to remove all productsof said preceeding operations;

and dyeing said bleached portions one color,

and the unbleached portions a complementary color, by means of dyes thatwill afi'ect only said portions respectively. 4

WILLIAM VAN DOREN KELLEY 7

